diff --git a/README.md b/README.md
index 4d3355e..8e1dddb 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,12 @@
 hello DOSdl
 ===========
-Hello DOSdl is a variant of Wordle / hello wordl for MS-DOS 1.25 and later.
+Hello DOSdl is a variant of Wordle / hello wordl for MS-DOS.
+
+System requirements
+-------------------
+
+- MS-DOS 1.25 or later, or PC-DOS 1.1 or later
+- 64KiB of RAM
 
 Gameplay
 --------